Optical Transceiver Module with Optical Windows

ABSTRACT

An optical module. The optical module includes an opto-chip. The opto-chip includes an integrated circuit with optical windows and a plurality of optoelectonic devices positioned in alignment with the optical windows. The plurality of optoelectronic devices are flip chip attached to the integrated circuit.

This invention was made with Government support under Contract No.:MDA972-03-3-0004 awarded by Defense Advanced Research Projects Agency(DARPA). The Government has certain rights in this invention.

BACKGROUND OF THE INVENTION

1. Field of the Invention:

The present invention relates generally to an improved data processingsystem. More specifically, the present invention is directed to anoptical transceiver module with optical windows for flip-chip attachedoptoelectronic devices.

2. Description of the Related Art:

Today, commercial parallel optical modules are based onindustry-standard 850 nanometer (nm) wavelength vertical cavity surfaceemitting laser (VCSEL) and photodiode optoelectronic (OE) devices.Typically, arrays of these OE devices are fabricated on a semiconductorsubstrate, such as gallium arsenide (GaAs) or indium phosphide (InP),which are low-cost materials. Optical input and output is directed toand from the top surface of the semiconductor substrate because GaAs andInP substrates are not transparent to a wavelength at substantially 850nm.

Typically, 850 nm wavelength OE devices are packaged in a side-by-sideconfiguration. That is, the OEs are electrically interconnected todriver integrated circuits (ICs) either by wire bonds or through anintermediate electrical carrier. Then, the ICs may be connected to thenext level package either by additional wire bonds or through additionalwiring on the intermediate electrical carrier. As a result, existingpackaging solutions may be complex, costly, and limited in high speedperformance due to electrical packaging parasitics.

SUMMARY OF THE INVENTION

Illustrative embodiments provide an improved optical module. The opticalmodule includes an opto-chip. The opto-chip includes an integratedcircuit with optical windows and a plurality of optoelectonic devicespositioned in alignment with the optical windows. The plurality ofoptoelectronic devices are flip chip attached to the integrated circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the invention are setforth in the appended claims. The invention itself, however, as well asa preferred mode of use, further objectives and advantages thereof, willbest be understood by reference to the following detailed description ofan illustrative embodiment when read in conjunction with theaccompanying drawings, wherein:

FIG. 1 is a block diagram of a side edge view of an optical transceivermodule in accordance with an illustrative embodiment;

FIG. 2 is a block diagram of a side edge view of an opto-chip with anintegrated lens array in accordance with an illustrative embodiment;

FIG. 3 is an illustration of a top view of an integrated circuit withoptical windows in accordance with an illustrative embodiment;

FIG. 4 is a block diagram of a side edge view of an optical transceivermodule with a ball grid array in accordance with an illustrativeembodiment;

FIG. 5 is a block diagram of a side edge view of an optical transceivermodule with a bottom mounted opto-chip in accordance with anillustrative embodiment;

FIG. 6 is a block diagram of a side edge view of an opto-chip withbackside mounted optoelectronic devices in accordance with anillustrative embodiment;

FIG. 7 is a block diagram of a side edge view of an optical transceivermodule attached to a system board in accordance with an illustrativeembodiment;

FIG. 8 is a block diagram of a side edge view of an optical transceivermodule with an attached optical fiber array in accordance with anillustrative embodiment; and

FIG. 9 is a block diagram of a side edge view of a multi-chip module inaccordance with an illustrative embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference now to the figures and in particular with reference toFIG. 1, an exemplary block diagram of an optical module apparatus isprovided in which illustrative embodiments may be implemented. It shouldbe appreciated that FIG. 1 is only exemplary and is not intended toassert or imply any limitation with regard to different illustrativeembodiments. Many modifications to the depicted optical module apparatusmay be made.

FIG. 1 depicts a block diagram of a side edge view of an opticaltransceiver module in accordance with an illustrative embodiment.Optical transceiver module 100 is an electrical and optical componentthat is capable of transmitting and receiving pulses of light, which areused to communicate data. Optical transceiver module 100 includesprinted circuit board (PCB) 102 and opto-chip 104.

PCB 102 mechanically supports and electronically connects electroniccomponents, such as opto-chip 104, to other electronic components. PCB102 may, for example, be an organic carrier, which is similar toconventional chip carriers. PCB 102 may also be a ceramic carrier.

PCB 102 includes cutout 105. Cutout 105 is an area that is cutout of PCB102 and is devoid of structure. Cutout 105 is used to accommodate aportion or all of the structure of opto-chip 104. Also, it should benoted that cutout 105 does not penetrate all the way through PCB 102. Inother words, cutout 105 does not create a hole through PCB 102.

Typically, cutout 105 is a square or rectangular area bordered by PCB102 on all four sides and on the bottom. However, it should be notedthat cutout 105 may be any regular or irregular geometric shape and maynot be entirely bordered by PCB 102. For example, cutout 105 may only bebordered by PCB 102 on three sides or two sides depending on whethercutout 105 is on an edge or a corner of PCB 102.

Opto-chip 104 is a chip-like device that is flip chip attached to PCB102. Flip chip offers increased high speed electrical performance. Flipchip is one type of surface mount technology (SMT) used forsemiconductor devices that does not require wire bonds. Eliminating bondwires may reduce the delaying inductance and capacitance of a connectionby a factor of ten and may shorten an electrical path by a factor of 25to 100. The result is a higher speed interconnection.

Opto-chip 104 includes IC 106. It should be noted that even though onlyone IC is shown in this exemplary illustration, IC 106 may alsorepresent a plurality of ICs. IC 106 is a single transceiver IC thatincludes both a transmitter component and a receiver component. Thetransmitter component of IC 106 may, for example, be a complementarymetal-oxide-semiconductor (CMOS) laser driver. The receiver component ofIC 106 may, for example, be a CMOS receiver chip.

Opto-chip 104 also includes OE 1 108 and OE 2 110. It should be notedthat OE 1 108 and OE 2 110 may represent 1×N arrays of OE devices, whereN may equal any positive whole number. In addition, OE 1 108 and OE 2110 may represent different types of OE devices.

In this exemplary illustration, OE 1 108 is a VCSEL. As a result,opto-chip 104 uses OE 1 108 as a transmitter to output pulses of light.In addition, OE 2 110 is a photodiode. As a result, opto-chip 104 usesOE 2 110 to receive light pulses as input. Consequently, transceiver IC106 acts as a laser driver, such as a CMOS laser driver, to modulate theoutput of light pulses from OE 1 108 to represent ones and zeros forcommunicating data. Further, transceiver IC 106 acts as a receiver chip,such as a CMOS receiver chip, to convert received light pulses from OE 2110 into electrical signals.

In an alternative illustrative embodiment, IC 106 may either act as atransmitter or as a receiver depending on the type of OE devicesattached to IC 106. For example, OE 1 108 and OE 2 110 may represent a2×N array of the same type of OE device. As a result, if OE 1 108 and OE2 110 are both VCSELs, then IC 106 is a laser driver and acts as atransmitter. Similarly, if OE 1 108 and OE 2 110 are both photodiodes,then IC 106 is a receiver chip and acts as a receiver.

OE 1 108 and OE 2 110 are positioned over optical windows 112. Opticalwindows 112 are small, vertical vias or holes through IC 106. Opticalwindows 112 allow optical input/output 114 to pass through IC 106 to andfrom OE 1 108 and OE 2 110. Optical input/output 114 represents lightpulses to and from optical circuits or fibers.

OE 1 108 and OE 2 110 electronically connect to IC 106 via conductivebumps 116. Similarly, IC 106 electronically connects to PCB 102 viaconductive bumps 118. Conductive bumps 116 and 118 may, for example, besolder bumps, gold balls, molded studs, or electrically conductiveplastics. Conductive bumps 116 and 118 connect directly to theassociated external circuitry. This type of mounting is also known asthe Controlled Collapse Chip Connection, or C4. In addition, this typeof mounting leaves a small space between the chip's circuitry and theunderlying substrate or mounting.

An electrically-insulating adhesive may be “under filled” in this smallspace to provide a stronger mechanical connection, provide a heatbridge, and to ensure conductive bumps 116 and 118 are not stressed dueto differential heating of opto-chip 104 and PCB 102. The resultingcompleted assembly (i.e., optical transceiver module 100) is muchsmaller than a traditional carrier-based system, both in terms of areaand height, because opto-chip 104 sits directly on PCB 102.

Thus, illustrative embodiments provide flip chip attachment of 2×N or1×N arrays of 850 nm wavelength OE devices directly onto a transceiveror driver/amplifier IC chip. The IC chip includes optical windows orvias under each OE device, such that input and output light pulses aredirected through the backside of the driver/amplifier IC chip.Conductive bumps or peripheral pads on the IC are used to flip chipattach the IC to an organic or ceramic carrier.

As a result, illustrative embodiments produce low cost, small footprint,parallel optical transmitters, receivers, or transceivers based on 850nm wavelength OE devices. The exclusive use of flip chip packaging toattach the OE devices to the driver/amplifier IC and thedriver/amplifier IC to an organic or ceramic substrate minimizes boththe footprint of the assembled optical transceiver module and theparasitic inductance and capacitance incurred in the connections betweencomponents. Consequently, illustrative embodiments allow production ofoptical transceiver modules with a plurality of parallel channels.Further, illustrative embodiments maximize the speed that may beobtained for each individual channel within the plurality of parallelchannels, such as, for example, greater than ten gigabits per second(Gb/s).

The IC chip may be fabricated using a standard CMOS fabrication process.An area, which does not contain circuitry, is reserved for the opticalwindows. Typically, the optical windows are circular areas withdiameters of 10 to 500 micrometers (um). Preferably, the area reservedfor the optical windows is near the center of the IC chip. Laser driverand photodiode receiver circuits my be designed with output bumps orpads near the optical windows. Peripheral conductive bumps or pads areprovided for attachment of the IC chip to the organic or ceramicsubstrate. These peripheral attachment points are used to transmitelectrical input and output signals to and from the IC chip. Typically,these conductive bumps or pads are 100 um on a 200 um pitch or 75 um ona 150 um pitch.

Once standard CMOS fabrication of the IC chip is completed, additionalprocessing of the wafer is used to fabricate the optical windows.Standard lithographic processes, such as, for example, photoresistapplication and photo exposure, are used to define the optical windows.The optical widows may typically have diameters in the range of 10 to500 um. Reactive ion etching (RIE) is used to etch nearly cylindricalfeatures in the silicon to a depth of 10 to 500 um. Backside grinding ofthe silicon wafer is used to thin the wafer to 10-500 um to expose theoptical windows.

Then, arrays of OE devices, such as VCSELs and photodiodes, are directlyflip chip attached to the IC chip using the OE attach pads on the ICnear the optical windows. The OE devices are positioned in alignmentwith the optical windows on the IC chip. A Gold-Tin (AuSn) solder alloymay, for example, be used for this flip chip attachment. The OE-ICassembly or opto-chip is then flip chip attached using the peripheralconductive bumps or pads to the organic or ceramic carrier. The organicor ceramic carrier may, for example, provide a conventional ball gridarray (BGA) of bond pads on the bottom surface for surface mounting to aconventional FR4 system PCB. Furthermore, lenses may be integrated intothe backside of the IC chip over the optical windows to provideefficient optical coupling between the OE devices and optical fibers orwaveguides.

With reference now to FIG. 2, a block diagram of a side edge view of anopto-chip with an integrated lens array is depicted in accordance withan illustrative embodiment. Optical transceiver module 200 may, forexample, be optical transceiver module 100 in FIG. 1. Opticaltransceiver module 200 includes PCB with cutout 202 and opto-chip 204.

Opto-chip 204 includes IC with optical windows 206 and OE 1 208 and OE 2210. OE 1 208 and OE 2 210 are positioned in alignment with the opticalwindows in IC with optical windows 206. Opto-chip 204 also includes lensarray 212. Lens array 212 is located on the “backside” of IC withoptical windows 206, whereas OE 1 208 and OE 2 210 are located on the“front side”. The “backside” of IC with optical windows 206 does notcontain any active circuitry, whereas the “front side” does includeactive circuitry.

Lens array 212 is an array of integrated lens that also are positionedin alignment with the optical windows. The number of integrated lenswithin lens array 212 may or may not correspond with the number of OEdevices flip chip attached to IC with optical windows 206. Lens array212 provides more efficient optical coupling between OE 1 208 and OE 2210 and optical fibers or optical circuits. In addition, lens array 212may provide for greater coupling distances between OE 1 208 and OE 2 210and the optical fibers or circuits by focusing the pulses of light tothe OEs. Optical input/output 214 represents the pulses of light thatare focused through lens array 212 to and from OE 1 208 and OE 2 210.

With reference now to FIG. 3, an illustration of a top view of anintegrated circuit with optical windows is depicted in accordance withan illustrative embodiment. It should be noted that FIG. 3 illustrates atop view of the “front side” of IC 300. IC 300 may, for example, be IC106 in FIG. 1. IC 300 includes circuit area 302, optical windows 304, OEattach pads 306, and peripheral I/O pads 308.

Circuit area 302 includes the active circuitry for one or more laserdrivers and/or one or more photodiode receivers. In addition, circuitarea 302 may also contain other types of circuitry in addition to thelaser drivers and photodiode receivers. For example, circuit area 302may also include decoupling capacitors, resistors, inductors, and/orintegrated active devices, such as voltage regulators, memory circuits,or other active circuits. The voltage regulators may, for example,provide the ability to regulate or segment voltages to each OE flip chipattached to IC 300 to support multiple voltage levels. In addition, thevoltage regulators may also provide an ability to power on and off OEsindividually.

The type of active circuitry within circuit area 302 depends on the typeof OE devices flip chip attached to IC 300. For example, if the OEs areVCSELs, then the active circuits within circuit area 302 include laserdrivers. Alternatively, if the OEs are photodiodes, then the activecircuits within circuit area 302 include photodiode receivers. However,if the OEs are a mixture of VCSELs and photodiodes, then the activecircuits within circuit area 302 include both laser drivers andphotodiode receivers.

Optical windows 304 may, for example, be optical windows 112 in FIG. 1.In this illustrative example, optical windows 304 are in a 2×8 array.However, it should be noted that illustrative embodiments are notrestricted to such. Illustrative embodiments may use any type of array,such as, for example, 1×N, 2×N, 4×N, 6×N, 8×N, et cetera. Typically, thenumber of optical windows 304 will correspond to the number of OEdevices flip chip attached to IC 300.

OE attach pads 306 may, for example, be conductive bumps 116 in FIG. 1.OE attach pads 306 provide for the flip chip attachment of OEs, such asOE 1 108 and OE 2 110 in FIG. 1, to IC 300. Typically, one OE attach padis located on each side of an optical window. Alternatively, both OEattach pads may be located on the same side of the optical window.

Peripheral I/O pads 308 may, for example, be conductive bumps 118 inFIG. 1. Peripheral I/O pads 308 provide for the flip chip attachment ofIC 300 to an organic or ceramic substrate, such as, for example, PCB 102in FIG. 1. In addition, peripheral I/O pads 308 are used to transmit andreceive electrical input/output signals between IC 300 and the organicor ceramic substrate.

With reference now to FIG. 4, a block diagram of a side edge view of anoptical transceiver module with a ball grid array is depicted inaccordance with an illustrative embodiment. Optical transceiver module400 may, for example, be optical transceiver module 200 in FIG. 2.Optical transceiver module 400 includes PCB with cutout 402 andopto-chip 404, such as PCB with cutout 202 and opto-chip 204 in FIG. 2.PCB with cutout 402 includes BGA 406. BGA 406 is an array of bond padsor conductive bumps on the bottom surface of PCB with cutout 402 forsurface mounting optical transceiver module 400 to, for example, asystem PCB, such as a motherboard.

With reference now to FIG. 5, a block diagram of a side edge view of anoptical transceiver module with a bottom mounted opto-chip is depictedin accordance with an illustrative embodiment. Optical transceivermodule 500 may, for example, be optical transceiver module 400 in FIG.4. Optical transceiver module 500 includes PCB with cutout 502 andbottom mounted opto-chip 504. It should be noted that bottom mountedopto-chip 504 is flip chip attached to the bottom side of PCB withcutout 502, whereas opto-chip 404 is flip chip attached to the top sideof PCB with cutout 402 in FIG. 4.

PCB with cutout 502 includes a cutout area on the bottom side toaccommodate a portion of bottom mounted opto-chip 504. In addition, PCBwith cutout 502 also includes BGA 506, such as BGA 406 in FIG. 4.However, it should be noted that BGA 506 does not extend into the centerarea on the bottom side of PCB with cutout 502 where bottom mountedopto-chip 504 is located. In addition, BGA 506 may comprise relativelylarger conductive balls, as compared to BGA 406 in FIG. 4, in order toaccommodate bottom mounted opto-chip 504 between optical transceivermodule 500 and a system PCB.

With reference now to FIG. 6, a block diagram of a side edge view of anopto-chip with backside mounted optoelectronic devices is depicted inaccordance with an illustrative embodiment. Optical transceiver module600 includes PCB 602 and opto-chip 604. PCB 602 includes cavity 603,which is a hole cut through PCB 602. Cavity 603 allows opticalinput/output 605 to pass through PCB 602 to a front side of IC withoptical windows 606.

Opto-chip 604 includes IC with optical windows 606, OE 1 608, and OE 2610. It should be noted that OE 1 608 and OE 2 610 are located on thebackside of IC with optical windows 606. In contrast, OE 1 108 and OE 2110 are located on the front side of IC 106 in FIG. 1.

Opto-chip 606 also includes electrical thru vias 612. Electrical thruvias 612 are small, vertical holes etched through IC with opticalwindows 606. Typically, one electrical thru via is located on each sideof an optical window, which is similar to the positioning of OE attachpads 306 adjacent to optical windows 304 in FIG. 3. RIE may, forexample, be used to etch electrical thru vias 612. In addition,electrical thru vias 612 may be filled with a metal, such as copper (Cu)or tungsten (W), or some other type of conductive material.

Electrical thru vias 612 electrically connect OE 1 608 and OE 2 610 to acircuit area on the front side of IC with optical windows 606, such ascircuit area 302 on the front side of IC 300 in FIG. 3. Thus, electricalthru vias 612 allow OE 1 608 and OE 2 610 to be packaged on the backsideof IC with optical windows 606.

In an alternative embodiment, OE 1 608 and OE 2 610 are located on thefront side of IC with optical windows 606, which contains the circuitarea. In other words, in this alternative embodiment the circuit area onthe front side of IC with optical windows 606 now faces away from PCB602. In contrast, the circuit area of IC 106 faces toward PCB 102 inFIG. 1. Thus, opto-chip 604 is now flip chip attached “upside-down” toPCB 602 in relation to opto-chip 104 in FIG. 1. As a result, conductivebumps 614, such as peripheral I/O pads 308 in FIG. 3, are located on thebackside of IC with optical windows 606 instead of the front side asillustrated in FIG. 3. OE 1 608 and OE 2 610 electrically connect to thebackside of IC with optical windows 606 via electrical thru vias 612,which are now vertically positioned over conductive bumps 614. OE 1 608and OE 2 610 now electrically connect to electrical thru vias 612, whichare repositioned over conductive bumps 614, via surface wiring.

With reference now to FIG. 7, a block diagram of a side edge view of anoptical transceiver module attached to a system board is depicted inaccordance with an illustrative embodiment. Optical transceiver module700 may, for example, be optical transceiver module 400 in FIG. 4.Optical transceiver module 700 includes PCB with cutout 702 andopto-chip 704. PCB 702 includes BGA 706. BGA 706 is used to surfacemount optical transceiver module 700 onto system board 708. System board708 may, for example, be a motherboard.

System board 708 includes interconnection 710. Interconnection 710 maycomprise conductive bumps or pads. Alternatively, interconnection 710may comprise sockets for receiving pin interconnections. In addition,interconnection 710 may represent a plurality of interconnection siteson system board 708. Interconnection 710 is used to attach other modulesor chips to system board 708.

With reference now to FIG. 8, a block diagram of a side edge view of anoptical transceiver module with an attached optical fiber array isdepicted in accordance with an illustrative embodiment. Opticaltransceiver module 800 may, for example, be optical transceiver module400 in FIG. 4. Optical transceiver module 800 includes PCB 802 andopto-chip 804. Opto-chip 804 includes lens array 806, such as lens array212 in FIG. 2.

Mechanical support structure 808 is attached to PCB 802. Mechanicalsupport structure 812 is an apparatus that is used to support and holdconnector 810. Connector 810 is located at each end of optical fiberarray 812. Connector 810 is used to physically connect or fasten opticalfiber array 812 to mechanical support structure 808. Mechanical supportstructure 808 also is used to align optical fiber array 812 over lensarray 806. Optical fiber array 812 may, for example, be a 2×N array ofoptical fibers for transmitting and receiving pulses of light, such asoptical input/output 814, which communicate data to and from opto-chip804 via lens array 806.

With reference now to FIG. 9, a block diagram of a side edge view of amulti-chip module is depicted in accordance with an illustrativeembodiment. Multi-chip module 900 is a module that incorporates thefunctionality of a plurality of electronic chips or devices. Multi-chipmodule 900 includes PCB with cutout 902 and opto-chip 904, such as PCBwith cutout 702 and opto-chip 704 in FIG. 7.

In addition, multi-chip module 900 also includes processor chip 906 andmemory chip 908. However, it should be noted that FIG. 9 is only shownas an exemplary illustration of a multi-chip module and is not meant asa limitation to illustrative embodiments. Consequently, multi-chip 900may include more or fewer chips. Moreover, multi-chip 900 may includeother types of chips in addition to, or instead of, processor chip 906and memory chip 908. Further, it should be noted that opto-chip 904,processor chip 906, and memory chip 908 are interconnected via wiring(not shown in the example of FIG. 9) on PCB with cutout 902.

Thus, illustrative embodiments provide an improved optical transceivermodule. The circuit as described above is part of the design for anintegrated circuit chip. The chip design is created in a graphicalcomputer programming language, and stored in a computer storage medium(such as a disk, tape, physical hard drive, or virtual hard drive suchas in a storage access network). If the designer does not fabricatechips or the photolithographic masks used to fabricate chips, thedesigner transmits the resulting design by physical means (e.g., byproviding a copy of the storage medium storing the design) orelectronically (e.g., through the Internet) to such entities, directlyor indirectly. The stored design is then converted into the appropriateformat (e.g., GDSII) for the fabrication of photolithographic masks,which typically include multiple copies of the chip design in questionthat are to be formed on a wafer. The photolithographic masks areutilized to define areas of the wafer (and/or the layers thereon) to beetched or otherwise processed.

The description of the present invention has been presented for purposesof illustration and description, and is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the art. Theembodiment was chosen and described in order to best explain theprinciples of the invention, the practical application, and to enableothers of ordinary skill in the art to understand the invention forvarious embodiments with various modifications as are suited to theparticular use contemplated.

1. An optical module comprising: an opto-chip that includes anintegrated circuit with optical windows and a plurality ofoptoelectronic devices positioned in alignment with the optical windows,wherein the plurality of optoelectronic devices are flip chip attachedto the integrated circuit, and wherein the optical windows are holes ona semi-conductor substrate containing the integrated circuit.
 2. Theoptical module of claim 1, further comprising: a carrier, wherein theintegrated circuit is flip chip attached to the carrier.
 3. The opticalmodule of claim 2, wherein the carrier is one of an organic substrate ora ceramic substrate.
 4. The optical module of claim 2, wherein theintegrated circuit is flip chip attached to a top side of the carrier.5. The optical module of claim 1, wherein the integrated circuit is atransceiver integrated circuit.
 6. The optical module of claim 2,wherein the integrated circuit is flip chip attached to a bottom side ofthe carrier.
 7. The optical module of claim 1, wherein the plurality ofoptoelectronic devices are flip chip attached to a front side of theintegrated circuit.
 8. The optical module of claim 1, wherein theplurality of optoelectronic devices are flip chip attached to a backside of the integrated circuit.
 9. The optical module of claim 8,wherein the plurality of optoelectronic devices flip chip attached tothe back side of the integrated circuit are electrically connected to afront side of the integrated circuit via electrical thru vias.
 10. Theoptical module of claim 7, wherein the front side of the integratedcircuit includes active circuitry.
 11. The optical module of claim 10,wherein the active circuitry is one or more laser drivers and one ormore photodiode receivers.
 12. The optical module of claim 1, whereinthe optical windows are small cylindrical holes that allow light pulsesto pass through the integrated circuit to the plurality ofoptoelectronic devices.
 13. The optical module of claim 2, wherein thecarrier includes a cavity that allows light pulses to pass through thecarrier to the optical windows in the integrated circuit.
 14. Theoptical module of claim 1, wherein the plurality of optoelectronicdevices include vertical cavity surface emitting lasers and photodiodes.15. The optical module of claim 1, wherein the plurality ofoptoelectronic devices operate at a laser wavelength of 850 nanometers.16. The optical module of claim 1, further comprising: a plurality ofchips in addition to the opto-chip, wherein the plurality of chipsprovide a plurality of different functions.
 17. The optical module ofclaim 1, wherein the opto-chip includes a lens array attached to a backside of the integrated circuit to provide efficient optical couplingbetween the plurality of optoelectronic devices and an optical fiberarray.
 18. The optical module of claim 1, further comprising: a firstset of conductive bumps for flip chip attachment of the integratedcircuit to a carrier; and a second set of conductive bumps for flip chipattachment of the plurality of optoelectronic devices to the integratedcircuit, wherein a pitch for the second set of conductive bumps is lessthan a pitch for the first set of conductive bumps.
 19. The opticalmodule of claim 1, wherein the integrated circuit is a transmitterintegrated circuit with laser driver active circuitry, and wherein theplurality of optoelectronic devices are vertical cavity surface emittinglasers.
 20. The optical module of claim 1, wherein the integratedcircuit is a receiver integrated circuit with photodiode receiver activecircuitry, and wherein the plurality of optoelectronic devices arephotodiodes.